Compensation Pendulums. 837 



it begins to rise, and continues till 1 1 p. m., and is then at the greatest 

 height, as at 9 in the morning." — Asiatic Researches, vol. x. p. 196. 



Beside the three periods mentioned in the above extract, Dr Balfour 

 found a fourth, as described in the following Table: — 



Barometer falls between 10 P. m. and 6 A. m. 



rises fi A. M. 10 A. m. 



falls 10 a. M. 6 P. m. 



rises 6 p. si. 10 p. m. 



Both Mr Farquhar and Dr Balfour considered these variations as con- 

 nected with the diurnal revolution of the earth. 



We may now add, that our countryman Colonel Wright seems to have 

 discovered, that these changes are made with such extraordinary regularity, 

 that the barometer may be almost used for measuring the lapse of time. 



In concluding these observations, we would recommend it to M. Arago 

 to desist from his repeated attacks upon English authors,* in which he 

 seems to take a peculiar delight, and which can have no other tendency 

 than to degrade science, and to exasperate national feeling, already too 

 highly excited. If a love of justice prompts him to this species of petty 

 warfare against England, how comes it that, in a paper on the Polarisa- 

 tion of Light, which he has written for the Supplement of the Encyclo- 

 paedia Britannica, he has almost entirely forgotten to record the exertions 

 of those who have laboured in that arduous field of inquiry. We can 

 easily understand why he has done injustice to Dr Brewster. We can 

 also understand why he has done injustice to Mr Herschel ; — it is suffi- 

 cient that they are both Englishmen. We can even understand why 

 he has suppressed the labours of Dr Seebeck, for he is a German ; but 

 we cannot understand why the important discoveries of M. Biot. his col- 

 league in the Academy, should have been so trampled upon and overlooked. 

 Those who have followed that distinguished philosopher in his wide 

 range of discovery ; and who have witnessed the prodigious ardour and 

 force of intellect which he has applied, to one of the most difficult 

 branches of scientific inquiry, will never cease to wonder that a presi- 

 dent of the Academy of Sciences should have dared to depreciate and sup- 

 press the labours of a man, who must ever be regarded by the philosophers 

 of all nations, as one of the brightest ornaments of his country. 



2. Bnjson's Compensation Pendulum, invented hy Mr David Ritchie of 



London. 

 In the article Horology of the Encyclopaedia Edinensis, a compen- 

 sation pendulum is described as the invention of Mr Bryson, watch- 

 maker in Edinburgh. This pendulum consists of two compound bars of 

 steel and brass placed at right angles to a steel pendulum rod, a little 

 above the ball. As the steel rod lengthens by heat, these compound bars 

 become more convex, and lift up the ball as much as it was depressed by 



• His attack upon the Rev. Dr Pearson was repelled by that able astronomer 

 with great spirit, and we hope that Mr Forster will be equally successful. 

 VOL. II. NO. II. APRIL 1825. Z 



